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[DPRG] Overvoltage protection

Subject: [DPRG] Overvoltage protection
From: Rick Bickle rbickle at intconsys.com
Date: Mon Sep 13 10:13:47 CDT 2010


A zener diode works, but they are generally low power. There are devices
called Transils, which can be purchased in 1.5kw to 5kw units AC or DC.
Also Teccor makes protection devices called Sidactors, which will clamp
an overvoltage similar to an SCR. These are commonly used for comm
circuits as they will clamp until the overvoltage condition is gone.



-----Original Message-----
From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org] On
Behalf Of Paul Bouchier
Sent: Saturday, September 11, 2010 9:19 AM
To: 'dprglist'
Subject: [DPRG] Overvoltage protection

Does anyone know a good overvoltage protection device suitable for
protecting a 5V regulated rail? I've now blown up 2 routers when they
being driven off a 78ST105 3-pin 5V switching regulator and am beginning
think that that device may go over voltage when battery input conditions

Low component count is valuable to me - I've seen the crowbar circuits
the 6.2V zener, but a 1-chip or 1-chip + 1 SCR or FET circuit would be
nicer. Either crowbar or FET pass transistor or other techniques would
fine. It would need to protect the output of the 78ST105 (1A capacity).

Thanks for any advice


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